The fierce debate on who is the best Portuguese player of all time that erupted when Cristiano Ronaldo overtook Eusebio last month to go second on the country's list of top marksmen is far from being settled.

Benfica's 1960s great Eusebio has weighed in to the argument, saying he was upset by what he considered to be an unfair comparison because he had played fewer matches than Ronaldo.

"I am saddened because we can't make that comparison. It's a mistake because I played (around) 60 matches to score that amount (41 goals)," Eusebio told Portuguese national television.

Ronaldo reached 43 goals in 106 internationals after his hat-trick earned Portugal a 4-2 comeback win over Northern Ireland in last month's World Cup qualifier.

"This is historic. I'd scored a lot of hat-tricks for Real Madrid but never any for Portugal," he said after the game.

"Going above Eusebio in the scorers' list was a natural thing to happen and it was only a matter of time but still I am really proud," the smiling player said while showing off the match ball.

Ronaldo has the chance to add to his tally on Friday in the home qualifier against Israel as Portugal seek to secure at least second place in Group F and a berth in the playoffs for next year's World Cup in Brazil.

While some of the football-mad Portuguese will angrily tell you not to compare the two because judging today's football against that of the 1960s is flawed, there are plenty of arguments on each side.

Ronaldo, 28, is set to rewrite Portugal's soccer statistics as he is only four goals behind top scorer Pauleta and 21 matches away from the most-capped player Luis Figo.

Striker Pauleta has said he does not consider himself equal to Eusebio, Ronaldo and Figo.

"Now, after all these years, someone else scores (that many goals) but obviously that happens because today it is easier to play some of these teams. I never got to play against Liechtenstein or Azerbaijan," he said.

Portugal have also been to the major tournaments more often with Ronaldo.

He has shone for his country at five major competitions, including the Euro 2004 final where they lost at Lisbon's Luz stadium to Greece.

Portugal also finished fourth at the 2006 World Cup in Germany and reached the semi-finals of Euro 2012.

Eusebio played at only one major tournament - the 1966 World Cup in England where he was the overall top scorer as Portugal grabbed a best-ever third place.

Portugal and Real Madrid's Pepe prefers his team mate.

"I hope Eusebio forgives me but, for me, the best player ever is Ronaldo. Despite his relatively young age, what he has already achieved for the 'Seleccao' leaves no doubts," he told sports daily o Jogo.

"Because of the goals he has scored and the clubs he has represented Ronaldo will leave a mighty footprint."

Ronaldo, a product of Sporting Lisbon's youth academy, has had a massive impact during his time with Manchester United, where he won the Champions League, and at Real Madrid.

Eusebio spent most of his career at Benfica, winning the 1962 European Cup and 11 league titles.

Those behind the 'Black Panther' say he excelled at a time when soccer science was limited.

"Eusebio had no preparation, no gyms, no academies. He became what he did through sheer talent," said Hilario Conceicao, former coach to Ronaldo and Figo.

His 1960s team mate Jose Augusto told o Jogo: "Footballs are all high-tech and vulcanised today, much faster, lighter and with unpredictable trajectories. With today's balls Eusebio would have scored double the goals."

Despite their differences the two players have a lot in common - devastating shooting, power and pace and the ability to use both feet.

"Technically the two are not actually that distant. Both are incredible hard-workers who loved to practice and improved from a very young age," said Jose Pereira, the head of Portugal's coach association.

"Ronaldo and Eusebio thrived thanks to a tremendous sense of opportunity up front and explosive runs," Pereira said. "Both are football giants."

That said, with Ronaldo still performing, a major international trophy or a player of the tournament award in Brazil next year would perhaps tilt the balance in his favour for good.